Effects of age on serum tryptophan and urine indican in adults given a tryptophan load test.
An oral load of L-tryptophan (490 mumol/kg) was administered to 25 men and 25 women between the ages of 30 and 80 years. Blood samples were drawn before the load and at 2-h intervals for 6 h after the load. Urine samples were collected for 5 days. Fasting serum tryptophan levels averaged 79.5 mumol/l (+/- 12.9 s.d.). Peak serum tryptophan levels (911-1002 mumol/l) occurred 2 h after the load. Urinary indican excretion on the day of the load averaged 6.4 mumol/24h/kg of body weight (+/- 2.8 s.d.). The concentration of tryptophan in serum, the amount of indican excreted in urine, and the indican:creatinine ratio in urine depended on the age of the subjects. The findings are discussed in relation to previous reports on effects of age on tryptophan pharmacokinetics.
D000328:Adult; D000368:Aged; D000375:Aging; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D007200:Indican / Q000652:urine*; D008297:Male; D008875:Middle Aged; D014364:Tryptophan / Q000097:blood / Q000378:metabolism*
D014364:Tryptophan; D003404:Creatinine; D007200:Indican